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Industrial processes produce vast amounts of heat. But when air or products need to cool down, this is typically vented to the environment as waste.
Industry accounts for nearly a third of the EU’s energy consumption. With fuel prices and carbon costs rising, waste heat recovery systems offer significant economic savings and could dramatically reduce carbon emissions.
In the EU-funded ETEKINA project, researchers focused on innovative heat pipe heat exchangers (HPHEs), systems that use arrays of sealed, fluid-filled tubes to recover heat from waste streams such as exhaust.
The team designed especially for three challenging industrial pilots. These prototypes are still in operation, far beyond the project’s completion, says Hussam Jouhara, technical coordinator of the ETEKINA project.
Advancing heat pipe technology
Heat pipes are an efficient tool used to recover heat from industrial processes. Like a refrigerator or an air conditioning unit , they use a boiling/condensation cycle inside a hermetically sealed metal tube to transfer thermal energy from one location to another.
HPHEs use many heat pipes working together in a contained system. As waste heat streams pass through the exchange, the heat pipes absorb the heat and transfer it to a heat sink fluid. The recycled heat then flows back to a point in the industrial process where it is needed.
The ETEKINA project developed three heat exchanger systems for three companies representing different industrial sectors: an aluminium car parts production facility in Spain, a steel foundry in Slovenia and a ceramic tile manufacturer in Italy.
“The project was conducted as a collaboration between the partners involved and was structured in a way that facilitated direct support to the end users by local project partners,” says Jouhara.
The HPHEs were designed and manufactured by the Heat Pipe and Thermal Management research group of Brunel University London, which Jouhara leads, and the heat exchange manufacturer Econotherm, with direct input from ETEKINA project partners to ensure the system was compatible with the intended processes.
“We managed to implement heat pipe technology to deal with extremely challenging waste heat recovery applications that were deemed impossible due to unstable flows, high temperatures and control compatibility with the process,” adds Jouhara.
Demonstrating the technology viability
The ETEKINA HPHE technology was found to reduce waste heat energy from all the industries involved by at least 40 %. The return on investment for the technology was nine months for the steel foundry, and less than 24 months for the other two installations. The units are still in operation, delivering large savings to the companies involved, especially in light of the increase in energy costs over the last two years.
“These installations secured stable and efficient recovery of very challenging waste heat streams back to the process,” notes Jouhara, adding that the project demonstrated the value of such HPHE efforts to industry.
Closing the loop on heat and water
The ETEKINA researchers are now pushing their technologies further to develop other recovery systems. The plan is to integrate these systems across European industries in the near future.
“The heat exchanger has gone through substantial development under another EU-supported project, iWAYS,” says Jouhara. He is also technical director of the iWAYS project, and inventor of the condensing technology that will be demonstrated through it in many locations across Europe. The aim is to further decarbonise European factories, and facilitate water recovery from industrial exhaust streams.
“ETEKINA demonstrated the heat pipe technology as a viable option for many other industries that were not featured,” concludes Jouhara. “It was an excellent example of how the European Horizon 2020 programme contributes directly to European industries.”